The present disclosure relates to compositions composed of grafted diene polymer and processes for producing the same.
Known are maleic anhydride (MAH) grafted olefin-based polymer resins (MAH-g-PO). Such resins are commonly used as tie layer in multilayer films for food packaging and specialty packaging. The MAH-g-PO tie layer is typically used to bind a polyolefin layer to other layers containing a polar substrate, such as nylon, for example. Currently, MAH-g-PO resin is produced via free radical grafting of maleic anhydride onto polyolefin in a melt blend process.
The art recognizes the benefits of MAH grafted ethylene/α-olefin/diene terpolymer. However, free radical grafting of an ethylene/α-olefin/diene terpolymer is problematic because the resultant MAH-g-ethylene/α-olefin/diene terpolymer has insufficient flow at elevated temperature (i.e., temperature above ambient) and low tensile strength. In addition, when the ethylene/α-olefin/diene terpolymer contains propylene comonomer, undesired chain scission side reactions (resulting in lower molecular weight and higher melt flow rate) occur during free radical grafting.
Desirable would be an ethylene/α-olefin/diene terpolymer with MAH functionalization that is flowable at elevated temperature and is not subject to crosslinking and/or chain scission during the production thereof.